Fingerprints are utilized as important evidentiary materials when criminals are specified in criminal investigations because fingerprints have characteristics of varying from person to person and remaining unchanged even after the elapse of a long period of time. In criminal investigations, criminals are specified by taking a photograph of a remaining fingerprint collected at a crime scene with a camera, incorporating the image of the remaining fingerprint into a fingerprint collation system, and detecting a fingerprint corresponding to the remaining fingerprint. Images registered with the fingerprint collation system are registered in dispersed states with respect to image quality and resolution because different people take photographs using different cameras. PTL1 below discloses a technique that improves collation accuracy of remaining fingerprint images in poor quality.